Catheter with novel lumens shapes

ABSTRACT

Catheter tubes of elastomeric material having novel lumen shapes which prevent occlusion and accommodate continued liquid flow even when kinked. Also, catheter tube slit valves are disclosed, the walls of which are not chemically weakened. Symmetrical and asymmetrical versions of said slit valves are disclosed. Combinations of highly reliable slit valves and catheter tubes are disclosed. Independently operable multi-lumen catheter assemblies of synthetic material, such as silicone rubber are disclosed, wherein the distal end of each lumen is normally closed by a three-position slit valve formed in a catheter tube covering. Multi-lumen catheters, and related methods, are also disclosed wherein the lumens are internal at the proximal and distal ends of the catheter tube but comprise separate tubes in between whereby, following placement of the distal end of the catheter tube in the body cavity of a patient, the unified proximal end of the tube is manipulated, sometimes subcutaneously, with the ultimately exposed tubes being thereafter severed and each equipped with a hub at a convenient exposed body site for selective independent passage of influent and effluent liquid along each lumen.

RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 160,473 filed Feb. 25, 1988, now U.S. Pat. No. 4,995,863 whichwas a continuation application of U.S. patent application Ser. No.915,477 filed Oct. 6, 1986, the latter having issued on Jun. 28, 1988 asU.S. Pat. No. 4,753,640.

FIELD OF THE INVENTION

The present invention relates generally to catheter slit valves andcatheters, catheters having slit valves and, more particularly, novelcatheters, catheter slit valve having extraordinary reliability and tomulti-lumen catheter assemblies, and related methods.

PRIOR ART

Prior to U.S. Pat. No. 4,327,722 those who proposed placement of a slitvalve in the wall of a catheter did so on the basis of the valve beingcontinuously open or where operation thereof is dependent uponunacceptably large pressure variations to open the valve. Chemicallyweakened slit valves provide high reliability.

It has become state of the art to extrude catheter tubing in cylindricalform where the catheter tubing has one or more lumens which are circularin transverse cross section. When this tubing is kinked, inadvertentlyor otherwise, the lumen or lumens are fully occluded and flow of liquidtherethrough is prevented.

U.S. Pat. No. 4,327,722, entitled Method for Intravenous Therapy andHyperalimentation, and like prior art discloses a single lumen flexiblesilicone rubber catheter which has one slit valve adjacent its closeddistal end. However, heretofore the use of distal end valves to normallyclose each lumen of a multi-lumen catheter has been rejected, especiallyfor silicone rubber multi-lumen catheters. See Reissue U.S. Pat. No.31,873 [U.S. Pat. No. 4,072,146]. Reissue U.S. Pat. No. 31,873 shows thementioned state of the multi-lumen catheter art, i.e. use of an externalsheath in which a random array of independent lumen-defining tubes areplaced wherein the distal tip of each lumen-defining tube comprises anopen port in an external sheath. Until the present invention, thesuperimposing of a valve at the interfacing site between eachlumen-defining tube of a multi-lumen catheter and an external sheaththereof was thought impossible.

Alternatively, a single lumen has been used at the distal end of acatheter, with the single lumen being joined to multi-lumens disposedaway from the distal end of the catheter. This approach, however,undesirably co-mingles liquids within the single distal end lumen, anddoes not allow independent use, perhaps simultaneous independent use, ofeach of several lumens.

The term "distal end", as used herein, refers to the forward end of thecatheter which is inserted into the patient's body. The term "proximalend", as used herein, refers to the rearward end thereof which remainsoutside the patient's body.

BRIEF SUMMARY AND OBJECTS OF THE INVENTION

In brief summary, the present invention comprises catheter tubes ofelastomeric material having novel lumen shapes which prevent occlusionand accommodate continued liquid flow even when inadvertently kinkedduring use.

Furthermore, in abbreviated summary as well, the present inventioncomprises catheter tube slit valves, the walls of which are mechanicallyweakened and which provide greater reliability, while avoiding the needfor large pressure variations during use. Symmetrical and asymmetricalversions of said slit valve are provided.

Also, novel combinations of highly reliable slit valves and cathetertubes are provided by the present invention.

The present invention also comprises sheathed independently operablemulti-lumen catheter assemblies of elastomeric material, including ultrasoft elastomeric material such as silicone rubber or polyurethane,wherein each lumen is independently operable and the distal end of atleast one lumen is normally closed by a three-position slit valvedisposed in an external covering or sheath laterally to one side of thelumen. The plurality of valve sites in the distal end portion of theexternal covering are disposed in spaced off-set relation Each slitvalve in the external covering normally closes the distal end of onelumen and comprises one or more two-way living hinges.

In addition, the present invention provides multi-lumen catheters, andrelated methods, wherein each lumen-defining wall is selectivelyexposed, but concealed at the proximal and distal ends whereby,following placement of the distal end of the catheter tube in the veinof a patient, the unified proximal end of the tube may be manipulated,sometimes subcutaneously, with the exposed tubes ultimately beingsevered and each equipped with a connector for selective independentpassage of influent and/or effluent liquid along each lumen.

With the foregoing in mind, it is an object of great significance toprovide elastomeric catheter tubes having novel lumen shapes.

A further paramount object is the provision of a catheter tube havingone or more lumens which are uniquely shaped so that occlusion of flowis prevented even when the catheter tube is inadvertently kinked.

An additional object of importance is the provision of novel highlyreliable catheter tube slit valves, which hingedly open and closewithout the need for chemically weakening of the material at the slitvalve.

Another dominant object is the provision of extraordinarily reliableslit valves in catheter tubes which avoid any need for large pressurevariations during use.

A further predominant object is the provision of novel highly reliablemechanically hinged catheter tube slit valves.

A further significant object is the provision of novel highly reliablesymmetrical and asymmetrical slit valves.

An object of primary importance is the provision of novel catheter tubesand slit valve combinations.

It is a further primary object of the present invention to provide novelmulti-lumen catheter assemblies, and related methods.

Another primary object of the present invention is the provision ofsheathed multi-lumen catheters assemblies.

A further important object of significance is provision of multi-lumensheathed catheters wherein the distal end of each lumen is normallyclosed by a three-position slit valve.

A further object of consequence is the provision of a multi-lumencatheter of synthetic resinous material wherein a three-position slitvalve is disposed in an external covering at the leading end of eachlumen.

An additional paramount object of the present invention is the provisionof a multi-lumen catheter of synthetic resinous material wherein theleading end of each lumen is closed by a three-position slit valveformed in an external covering, each slit valve comprising at least onetwo-way living hinge which is either eccentrically or symmetricallydisposed.

A further predominant object of the present invention is the provisionof multi-lumen catheters, and related methods, wherein eachlumen-defining tube is selectively exposed and concealed whereby asingle external proximal end and a single external distal end areprovided for placement purposes, following which the exposed wallsforming the lumens can be severed and each receive a connector forindependent use of each lumen.

These and other objects and features of the present invention willbecome apparent from the detailed description taken with reference tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-8 are transverse cross sectional views of catheter tubesembodying the principles of the present invention, each having one ormore novel lumen shapes which prevent occlusion and accommodatecontinued liquid flow even when inadvertently kinked;

FIG. 9 is an enlarged transverse cross section of the distal end ofanother two-lumen catheter embodying the principles of the presentinvention;

FIG. 10 is a perspective representation of a three-lumen catheterfabricated in accordance with the principles of the present invention;

FIG. 11 is an enlarged transverse sectional view taken along the lines11--11 of FIG. 10, showing a larger primary and two smaller secondarylumens;

FIG. 12 is a cross sectional view of a similar catheter showing onelarger primary lumen and one smaller secondary lumen only;

FIG. 13 is an inverted enlarged longitudinal fragmentary sectional viewtaken along the lines 13--13 of FIG. 11, showing the distal end portionof the catheter including two three-position slit valves, and alsoshowing a removable insertion stylet abutting the closed distal tip ofthe catheter;

FIG. 14 is an enlarged fragmentary exploded elevation of the proximalend of one lumen-defining tube of the catheter of FIG. 1 with the styletpartially removed;

FIG. 15 is an enlarged longitudinally-directed fragmentary cross sectionof the distal end portion of another multi-lumen catheter embodying theprinciples of the present invention;

FIG. 16 is a plan view of still another multi-lumen catheter of thepresent invention, showing two coupling sites one of which is brokenaway for clarity of illustration;

FIG. 17 diagrammatically and fragmentarily illustrates sites where theexposed lumen-defining tubes of the catheter of FIG. 16 are severedduring placement of the catheter preparatory for use;

FIGS. 18 and 19 diagrammatically and fragmentarily illustrate theinstallation of a connector in the form of a hub to the severed end ofeach lumen-defining tube; and

FIGS. 20 and 21 illustrate in exploded fragmentary perspective andfragmentary cross section, respectively, the construction of theconnector of FIG. 10.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference is now made to the drawings, which illustrate severalpreferred embodiments of the present invention. Like numerals are usedthroughout the drawings to reference like parts.

Specific reference is made to FIGS. 1-8, which illustrate in transversecross-section several catheter tubes embodying the principles of thepresent invention, each having one or more novel lumen shapes whichprevent occlusion and accommodate continued liquid flow, even wheninadvertently kinked, bent, twisted or collapsed. FIG. 1 comprises agenerally cylindrical catheter tube 30, formed of a body of elastomericmaterial 32 defining an outside smooth cylindrical surface 34 and asingle D-shaped axial lumen 36. The lumen 36 comprises linear wallsurfaces 38, 40 and 42. Linear wall surfaces 38 and 40 are joinedtangentially by a small diameter fillet corner 44 and surfaces 38 and 42tangentially by a small diameter fillet corner 46. Linear wall surfaces40 and 42 are joined tangentially by an arcuate wall surface 48.

The location and shape of the corners 44 and 46 define a relatively thindimension 50 through the body 32, which makes the D-shaped lumen 36amenable to utilization of certain slit valves fashioned in accordancewith the principles of the present invention, as hereinafter more fullydescribed. Furthermore, the nature and shape of the lumen 36 has shownthrough experimentation to prevent occlusion of the lumen 36 of thecatheter tube 30 when the same is kinked, bent, twisted or collapsed. Tothe contrary, catheter tubing according to the prior art, which utilizesthe cylindrical exterior surface and one or more cylindrical internalhollow lumens will result in total occlusion of the lumen or lumens whensuch prior art catheter tubing is, for example, kinked upon itselfthrough essentially 180 degrees.

The embodiment of FIG. 2, generally designated 30', is substantiallyidentical in all respects to the catheter tubing 30 of FIG. 1, exceptthat the surfaces 40' and 42' are somewhat shorter in their transversedimension than previously described wall surfaces 40 and 42. Thenon-occluding characteristic of catheter tubing 30 also exists whencatheter tubing 30' is used.

Likewise, catheter tubing 30" (FIG. 3) is substantially similar topreviously described catheter tubing 30 and 30', identical numeralsbeing used to identify substantially identical parts. Catheter tubing30" differs from catheter tubing 30 in that the flat wall surfaces 40"and 42" are of a substantially smaller width than wall surfaces 40 and42. Furthermore the fillet corners 44' and 46' are substantially largerin radius and arc distance than corners 44 and 46 and do notrespectively join the adjacent wall surface tangentially. Accordingly,lumen 36" is somewhat smaller than lumen 36 with modified cornerstructure at each end of the reduced size flat wall surface 38'.

Reference is now made to FIGS. 4-6, which illustrate, respectively,double-lumen catheter tubes 52, 54 and 56. To the extent that cathetertubes 52, 54 and/or 56 have physical parts corresponding to heretoforedescribed catheter tubes 30, 30' or 30", identical numerals are used onFIGS. 4-6 and no further description of those physical parts is deemednecessary to an understanding of the present invention.

Catheter tube 52 comprises primary lumen 60 and secondary lumen 62, eachof which define a relatively short distance 50 between an angular lumencorner and the external surface 34 of the catheter tube. The cathetertube 52 comprises an internal body of material 64 which defines andseparates the two lumens 60 and 62. Lumen 60 comprises a centrallydisposed flat wall surface 66 interposed between two other flat wallsurfaces 68 and 70. Wall surface 66 joins wall surface 68 tangentiallyvia corner 72 and wall surface 70 via corner 74. Wall surface 68 and 70are non-tangentially joined directly one to another by an arcuate wallsurface 76, which merges tangentially with the wall surfaces 68 and 70at fillet corners 78 and 80, respectively.

Catheter tube 52 further comprises a secondary lumen 62, as mentionedabove, lumen 62 comprising heretofore described wall surface 38 andfillet corners 44 and 46 tangentially joining relatively small flat wallsurfaces 40" and 42" to surface 38. Wall surface 40" is joined angularlyor nontangentially at site 82 to a linear wall surface 84, whichtangentially merges with an arcuate wall surface 86. Wall surface 42"likewise joins a flat upwardly angularly directed wall portion 88 atfillet corner 90. Wall portion 88 merges tangentially with arcuate wallportion 86. Thus, catheter tube 52 provides two aligned lumens whichprovide the relatively short corner spaces 50 to accommodate utilizationof highly reliable slit valves as hereinafter more fully explained andwhich, when the catheter tube 52 is kinked upon itself, will stillaccommodate liquid flow, as mentioned above.

Double lumen catheter tube 54 is illustrated in FIG. 5. Tube 54 providesinternal body and wall structure 64 which provides for separatedefinition of the two spaced lumens 36'. These lumens, while beingsomewhat different in size, are substantially identically shaped andeach corresponds substantially to the lumen 36' of FIG. 2 alreadydescribed.

Catheter tube 56 (FIG. 6) comprises a primary D-shaped lumen 92 and asecondary D-shaped lumen 62. Lumen 92 is substantially identical topreviously described lumen 36", except the rounded corners 44' and 46'are replaced by diagonally disposed non-tangential wall surfaces 94 and96, respectively. Diagonal wall surface 94 joins wall surface 40" atangular corner 98 and surface 38, at angular corner 100. Likewise,diagonal wall surface 96 joins wall surface 42" at angular corner 102and wall surface 38' at angular corner 104. Lumen 62 was heretoforedescribed in connection with catheter tube 52 See FIG. 4.

The non-occluding catheter tubes according to the present invention maycomprise more than two lumens defined within the catheter. For example,FIGS. 7 and 8, to which reference is now made, illustrate cathetertubes, according to the present invention, which comprise three lumens,respectively. The catheter tube of FIG. 7 is generally designated 106and the tri-lumen catheter of FIG. 8 is designated generally as 108.

Catheter tube 106 comprises one primary and two secondary lumens 36".Catheter tube 38' was described earlier in conjunction within FIG. 2.Accordingly, no further description is deemed necessary in respect tothe lumens of catheter tube 106, except to say that the lumens areillustrated as being disposed, respectively, along predetermined radiallines, consistent with the requirements of structural integrity neededfor indwelling catheters and so as to provide corner sites 50.

Likewise catheter tube 108 comprises one primary and two secondarylumens 62, previously described in conjunction with catheter 56, shownin FIG. 6. No further description is, therefore, deemed necessary, itbeing understood that the lumens 62 of catheter tube 108 are illustratedas being arranged along predetermined radial lines so that the corners44 and 46 thereof create corner sites at locations 50.

It is presently believed that the relatively thin regions 50 coupledwith the adjacent lumen corner structure accounts for the aforementionednon-occluding feature of catheter tubes according to the presentinvention.

Not only do the novel lumen shapes for catheter tubes according to thepresent invention prevent occlusion of the lumens where the cathetertube is kinked, flattened, or the like, the novel lumens have been foundto aid materially in the provision of novel slit valves according to theinvention.

Two such hinge action slit valves 35 and 35' are illustrated in FIG. 9.

FIG. 9 shows the distal end portion of two-lumen catheter 54, describedearlier in conjunction with FIG. 5 and having D-shaped primary andsecondary lumens 36'. The distal end portion of tube 54 comprisesexterior covering 32 and internal wall structure 64, which defines thelumens 36. Corners 44 and 46 of the lumens 36' are located closer to theexterior covering surface 34 than any other part of the lumens 36'.Thus, corners 44 and 46, in each case define two hinge or fold lines orregions 50 where the catheter wall is thinnest. Relatively thicker areas136 are disposed between hinge sites 50, thereby to define, betweeninner wall surface 38 and exterior covering surface 34 radiallyoutwardly therefrom, a solid outer wall portion of catheter 54integrally formed of the same material thereas. The distance betweeninner wall surface 38 and exterior covering surface 34 radially outwardtherefrom defines the thickness of relatively thicker areas 136. As seenin FIG. 9, the thickness of relatively thicker areas 136 varies from amaximum at the center thereof to a minimum at thin regions 50, the endsthereof. The slit 138 of slit valve 35 is symmetrically disposed along aradial line equidistant between the hinge sites 50 of the primary lumen36'.

The D-shaped lumens 36' are structurally stronger than conventionalround catheter tube lumens. Therefore, lumens according to the presentinvention are more resistant to collapse under high negative pressures.The D-shaped lumens also offer two principal advantages in the operationof the valve 35. First, the thicker walls adjacent the self sealing slit138 create a larger sealing surface area for the valve lips 136, and,therefore, create a more positive seal when the distal end portion oftube 54 is indwelling and under normal physiological pressures. Second,the flex of the valve 35 is concentrated at the hinge sites 50, whichsites are located some distance from the slit 138. This concentration ofthe flex in a relatively small hinge site provides for more consistentoperation, more reliable response to predetermined pressuredifferentials designed to open and close the valve, a wider valveopening, and a longer life of the valve 35. The use of thickened valvelips 136 also serves to raise the withdrawal threshold, providing for amore positive, highly reliable valve action.

FIG. 9 also diagrammatically illustrates an eccentric slit valve 35'comprising a single slit 141 disposed in one corner 46 of the secondarylumen 36'. In this configuration, the hinge action is concentrated atthe single hinge site 141, illustrated as intersecting the other lumencorner 44. Thus, the entire asymmetrical valve lip 142 is hingedlydisplaced, inwardly or outwardly, to create the valve orifice. Thiseccentric configuration accommodates, with high reliability, use of theslit valve 141 in catheters having lumen sized too small to provideconsistent operation of a symmetrical slit valve. The two slit valvesillustrated in FIG. 9 are shown, for ease of illustration, as being inthe same transverse plane. However, in actual fabrication the slitvalves are preferably longitudinally and radially offset each from theothers. In limited testing to date, the eccentric valve 35' has provedbetter in use than concentric valve 35, where the catheter lumen sizewas relatively small.

It is to be understood that the present invention embraces theaforedescribed slit valves comprising one or more mechanically weakenedhinge regions independent of whether the wall regions of the slit valvesare or are not chemically treated.

Specific reference is made at this time to FIGS. 10-14 which illustratea further presently preferred catheter, generally designated 230,fabricated according to the principles of the present invention. FIG. 10shows the catheter 230 to comprise several major parts: i.e. 1) a distalend portion 232, adapted for insertion into a vein or other body cavityof a medical patient and comprising an exposed external sheath orcovering 233 and internal wall structure 255, which defines a pluralityof independent and separately operable circular lumens for carryingliquids to or from a desired body cavity; 2) a three-position pressureactivated slit valve 234 forming a normally closed lateral gate or portshown as being disposed at the distal end of each catheter lumen, eachslit valve 234 being controlled by the application of positive ornegative pressures to the associated lumen of the catheter 230; 3) acoupling or transitional member 236 connecting the distal end portion232 to a proximal end portion 237 which comprises a number oflumen-defining tubes 238; 4) the proximal end portion 237 of thecatheter 230 comprising tubes 238 which respectively extend the lumensof the catheter to exposed hubs 240, of a conventional type, whichaccommodate connection to various fluid infusion and withdrawal and likedevices; and 5) terminal hubs 240, each shown as being closed by aconventional plug 241.

Each three-way valve 234 normally prevents flow but provides forselective positive control of the liquid flow only through theassociated lumen. By applying a predetermined positive pressure to thelumen terminal hub 240, with the stopper 241 removed, a desired liquidis infused into the vein of a patient by forcing the associated valve234 to hingedly open. By applying a negative pressure, liquid within abody cavity is withdrawn. Under normal physiological pressures, thevalve 234 will remain closed and sealed.

The distal end portion 232 is typically cylindrical in shape, as shownin FIG. 2. However, the exterior surface may take other forms. Thedistal end portion 232 is preferably slender in diameter, allowing theclosed distal tip 242 to be facilely introduced into a vein or othercavity and advanced to a desired treatment location, while the proximalend 237 remains outside the body. The length of the distal end portion232 will, therefore, vary with its intended application. The distal endportion 232 is illustrated as having a uniform though relatively smallexterior diameter so that it can be readily inserted into a vessel, suchas the subclavian vein, without causing undue trauma to the patient.Typically, this requires that the distal end portion 232 have an outsidediameter not exceeding about 0.125 inches (0.318 cm). The distal tip 242of the distal end portion 32 is preferably dome-shaped and smoothed tofurther minimize trauma.

As shown in FIG. 13 (in inverted and angular sectional view with respectto FIG. 11), the array of slit valves 234 is formed in the sheath 233and exposed at the exterior cylindrical surface 248 thereof, at site243. Each valve 234 is also exposed laterally to one of the lumens, atsites 245. The valve sites are radially distributed in offset relationaround the distal end portion 232 near the tip 242 so that no two valves234 lie in any one radial plane. The valves 234 are also longitudinallyseparated or offset in their placement at relatively short but differentdistances from the distal tip 242 so that no two valves 234 lie in anyone axial plane. The radial and longitudinal separation of the valves234 helps avoid structural weakness and helps prevent possiblecontamination of an influent sample withdrawn from one valve 234 by aninfusion stream of effluent liquid from another valve 234 passing intothe vein of a patient, which might adversely affect test results orresult in premature mixing of incompatible therapeutic liquids. Itshould be noted that longitudinal separation should not be used wherethe effect would be to position any valve 234 out of the desiredtreatment or exposure area.

The distal end portion 232 is made of a durable and pliable yetshape-retaining biocompatible synthetic elastomeric material. It ispresently preferred that the material comprise an ultra soft syntheticmaterial. Typically, such material should have a hardness of less than100 durometer and an elongation percentage of up to 700. A preferredmaterial is a silicone rubber tubing having a hardness of about 59durometer sold under the trade name SILASTIC by Dow Corning Co.,Midland, Mich. The distal end portion 232 is preferably at leastpartially radiopaque so that its precise position in the body may beradiologically verified. Tubes 237 are preferably transparent so thatthe physician can visually determine the presence of air bubbles, blood,or other liquids in each of the lumens during and after insertion.

As illustrated in FIG. 11, three independent lumens 252, 253 and 254 arelongitudinally disposed inside the distal end external covering 233, thelumens typically being radially distributed at predetermined anglesbeneath the exterior cylindrical surface 248 of the distal end portion232 in such a way that an interior lumen wall surface passes within arelatively short distance of the exterior surface 248 of the exteriorcovering 233, as measured along a radial line passing through the centerof each lumen 252, 253 and 254. It is apparent from the radialdisposition of the lumens in close proximity to the exterior surface 248that valves 234 installed along a radial line in the fashion justdescribed or installed in any consistent position relative to the lumens252, 253, and 254 will necessarily be radially separated from each otheras previously discussed. Interior walls 255 (FIG. 11) respectively formand define the size and shape of the lumens 252, 253 and 254 at thedistal end portion 232. Tubular, hollow walls 257 respectively form anddefine the size and shape of lumens 252, 253 and 254 at the proximal endportion 237.

Note from FIG. 12 that a double lumen catheter having a proximal endportion 232' is also within the scope of the present invention. Proximalend portion 232' comprises primary lumen 252 and secondary lumen 253'.

Each lumen 252, 253 and 254 extends from the associated hub 240 at theproximal end portion 237 to a point near the distal tip 242. See FIG.10. The larger or primary lumen 252 extends substantially the entirelength of the catheter 230, terminating in a closed tip wall portion 262adjacent the distal tip 242 of the distal end portion 232. See FIG. 13.Secondary lumens 253 and 254 terminate in similar closed end wallportions 263, only one of which is illustrated in FIG. 13. The lumensterminate at relatively short but different distances from the distaltip 242, for the purpose of providing longitudinal separation of thevalves 234, as previously described.

In the embodiment of FIGS. 10, 11, and 13, the proximal end portion 232is preferably formed by extrusion, for reasons of simplicity and ease ofconstruction, but other methods may be used. When extruded, the lumens252, 253 and 254 and the interior walls 255 forming the lumens 252, 253and 254 are continuously formed during extrusion; thus, each lumen is ofa uniform cross-sectional shape, being cylindrical or circular in theembodiment of FIGS. 10, 11 and 13.

In the extruded embodiment of FIGS. 10, 11 and 13, the closed end wallportions or plugs 262 and 263 are formed by injecting a suitablesilicone rubber adhesive or the like into the leading ends of lumens252, 253 and 254 for the distance from the distal tip 242. The adhesivethen hardens to form the closed end wall portions or plugs 262 and 263,each up to the leading edge of the associated valve 234. If a radiopaquedistal tip 242 is desired, this may be accomplished by mixing aradiopaque material with the adhesive prior to injection to form plugs262 and 263.

One three-position valve 234 is placed in the covering adjacent to andlaterally interfacing with each lumen 252, 253 and 254 adjacent the plug262 or 263. Each valve 234 is formed by a single relatively short slit266 in the covering 233. Each slit extends longitudinally along theexterior of covering 233 parallel to but offset from the axis of thedistal end portion 232. The thickness of each slit valve 234 is equal tothe thickness of covering 233, so as to provide for selective liquidcommunication between the interior of the lumen 252, 253 and 254 withthe exterior of the distal end portion 232. Each slit valve 234 isillustrated as being radially directed and symmetrically disposed in itscorresponding lumen 252, 253 and 254 at the thinnest point in thecovering 233. Thus, each slit valve 234 comprises two valve lips orwalls 270 which comprise blunt edges. These edges contiguously mate andseal along the slit 266 under normal indwelling pressure conditions.

FIG. 11 shows the operation of each three-position slit valve 234. Uponapplication of a predetermined pressure differential between theinterior and exterior of the distal end portion 232, the valve wall willhingedly deflect or flex causing the valve lips 270 to separate at slit266, creating a flow path-defining orifice through which liquid may passin or out of the selected catheter lumen 252, 253, 254, when the distalend portion 232 is indwelling. When the indwelling pressure inside theselected catheter lumen 252, 253, 254 exceeds the indwelling pressureoutside the distal end of the catheter by a predetermined amount (the"infusion threshold"), the valve immediately surrounding the slit 266deforms, and the lips 270 of the valve 234 are caused to separatehingedly in an outward direction thereby creating an orifice throughwhich liquid is infused into the blood stream, as shown in FIG. 11.Likewise, the application of a sufficient degree of negative pressure(the "withdrawal threshold") to the selected catheter lumen 252, 253,254 will cause the valve lips 270 to flex hingedly inwardly, also asshown in FIG. 11, allowing withdrawal of blood or other fluids from thebloodstream or other body cavities.

Under normal physiologic conditions, as stated above, each slit valve234 remains closed and sealed, as shown in solid lines in FIG. 11. Thisrequires that the catheter tube have sufficient memory to return to theclosed sealed edge-to-edge position when liquid flow conditionsterminate. When used in the cardiovascular system, the withdrawalthreshold must also be high enough to prevent back bleeding under normalsystolic pressures in the circulatory system of a patient. The infusionthreshold must likewise be high enough to overcome the normal venturieffect of blood flowing past the indwelling valve 234. The infusion andwithdrawal thresholds should not be so high as to make infusion orwithdrawal difficult.

Both the infusion and the withdrawal thresholds can be adjusted eitherby controlling the thickness and configuration of the valve walls orlips 270 or by selectively treating the valve walls with a biocompatiblesoftening agent such as dimethylsiloxane, as is more completelydisclosed in U.S. patent application Ser. No. 491,258, filed May 3,1983, now U.S. Pat. No. 4,549,879. It should also be noted that thevalve 234 may, if desired, be treated with an anticoagulant, such asHeparin. However, the design of the catheter 230 disclosed herein doesnot require such treatment.

The liquid flow capacity of the lumens may vary with the intendedapplication of the catheter 230. The lumens must course, be large enoughto accommodate the desired fluid flow, while the thickness of the wallsforming the lumens must be adequate to prevent rupture or inadvertentpuncture and consequent leakage either between lumens or to or from theexterior.

The slit valve 234 must be the weakest point in each lumen 252, 253 and254. Each part of each catheter lumen must be stronger and more rigidthan the valve lips 270, since collapse or rupture of any other part ofthe catheter would defeat the purpose of the catheter 230. It is,therefore, important that the lumen walls be strong enough to stand thefull range of lumen pressures without rupture, inward collapse or otherfailure, which would impair proper operation of the slit valves 234.

While from a practical point of view, the utilization of a singleextruded tube comprising multiple lumens for the distal end portion 232is effective and low-cost, it is to be appreciated that the distal endportion 232 can be otherwise fabricated. For example, with reference toFIG. 15, the distal end 232" may comprise separate spaced lumen-definingtubes 274, 276 disposed within a hollow cavity 278 of an external thinwalled cylindrical sheath or covering 233', which has a smoothcylindrical exterior surface 248'. The proximal edges of the tubes 274,276 are secured by satisfactory adhesive to the interior of the sheath233' at sites 280. The resulting lumens 252' and 253" respectivelytransversely interface with a slit valve 234 disposed in the wall of thesheath 233'. No further discussion of the slit valve 234 is deemed to benecessary in light of the prior description thereof The distal tip 242'of the distal end portion 232" is configured so as to be shapedsubstantially the same as the heretofore described distal tip 242. Thetip 242' does provide an internal circular transverse flat wall 283against which an insertion stylet or insertion stiffener abuts whenplaced within the primary lumen 252', in a manner and for purposeshereinafter more fully described.

Returning now to the embodiment of FIGS. 10, 11 and 13 the proximal endportion 237 of the catheter 230 is joined via a connector 236 to aplurality of separate lumen-defining tubes 238. Tubes 238 may be made ofan ultra-soft synthetic material or other elastomer, similar to thematerial of the distal end portion 232, previously described. However,the tubes 238 must be strong enough to resist collapse or rupture andthe additional environmental hazards of an exposed tube. Each tube 238may, therefore, be strengthened by using a tubing with thicker wallsand/or a higher durometer. Tubes 238 are preferably at least partiallytransparent or translucent to accommodate visual monitoring of thecontents therein. Unlike distal end portion 232, however, the proximaltubes 238 have no need for radiopacity, because they are not intended tobe indwelling.

Tubes 238 are most economically constructed of a tubing with concentricinner and outer cylindrical wall surfaces, thereby forming walls ofuniform thickness providing a predetermined inside diameter equal tothat of lumens 252, 253 and 254 of distal end portion 232. The outsidediameter of connector tubes 238 should be large enough provide a wallthickness at 257 adequate to resist abrasion and puncture. The trailingedge of each tube 238 is preferably perpendicular to the axis thereof.This accommodates connection of hub 240 at short hollow shaft 282thereof, using a sleeve coupling 284. See FIGS. 11 and 14. Each sleevecoupling may be secured in the stated and illustrated position usingconventional material-shrinking techniques.

The connector 236 is constructed by permanently connecting each lumen252, 253 and 254 to one of the tubes 238 by use of a hollow couplingtube 285. See FIG. 20. Each coupling tube 285 may be made of surgicalsteel, although other materials can be used. Preferably each couplingtube 285 has an inside diameter substantially the same as the insidediameter of the catheter lumen 252, 253, 254, to which it is attached soas to minimize if not prevent any flow restriction at the connector 236.The outside diameter of each coupling tube 285 should, therefore, beslightly larger than the inside diameters of lumens 252, 253, 254 andtubes 238. Thus, each tube 285 is force fit into lumens 252, 253, 254 atthe body of connector 236, expanding each at the insertion sites. Theleading end 297 of each tube 238 is force fit over the trailing end ofthe associated connector tube 285. See FIG. 21.

The entire joint or connector 236 is preferably secured with siliconerubber adhesive 264 or other appropriate sealant, and finallyshrink-wrapped by soaking a tubular silicone rubber sleeve 296 in Freonor other solvent material causing it to temporarily expand, and slippingthe sheath 296 over the connector 236. As the solvent evaporates thesheath 296 permanently contracts firmly around the remainder of theconnector 236, adhering to the adhesive 264 and forming a secure andprotected joint.

Suture wing 298 is illustrated as being attached to the connector 236 sothat the catheter 230 at connector 236 may be sutured in place after thedistal end thereof is indwelling. The suture wing 298, shown in FIGS.10, 20 and 21 is fashioned from a small piece of silicone rubber sheetcut in the illustrated elongated shape and having circular holes 300disposed in the ends thereof to receive sutures. Suture wing 298 mayalso help to prevent the catheter 230 from rolling or shifting whentaped in place on a patient as opposed to suturing in place. The suturewing 298 is preferably attached to the connector 236 using siliconerubber adhesive or another suitable method.

When the catheter tube 232 is formed of soft, pliable material, a styletor inserter 306 is preferably used to rigidify the distal end portion232 during insertion. In the illustrated embodiment, stylet 306 isillustrated as being formed of twisted surgical grade wire. The stylet306 is illustrated as being equipped with an integral proximal hub 307,by which the stylet is manipulated. See especially FIGS. 13 and 14. Itcould also be formed of any yieldable and shape retaining biologicallyinert material such as polypropylene. Stylet 306 is preferably insertedinto the primary lumen 252, until its distal tip 308 abuts the closedwall 262. During insertion, a force manually applied to the stylet 306causes the distal end thereof 308 to push against closed end 262 of theprimary lumen 252. This places the covering 233 under tension, causingthe distal end portion 232 to be pulled forward into the vein of thepatient, for example.

Primary lumen 252 must naturally be dimensioned large enough toaccommodate the stylet 306. The walls 255 defining the primary lumen 252and the covering 233 should also be thick enough to prevent accidentalpenetration by the stylet 306, which could result in undesiredcommunication between lumens or trauma to the patient.

The stylet tip 308 should also be constructed to prevent penetrating theprimary lumen 252 through the slit valve 234 or through the tip or head242. In this regard, the abutment 262 of primary lumen 252 may be formeda sufficient distance from the slit valve 234 to allow an adequatesafety margin against stylet damage at the valve site 234.

The distal tip 308 of stylet 306 is kept in constant pressure contactwith the abutment 262 of primary lumen 252, during storage andinsertion, as shown in FIG. 13. The stylet 306 is of slightly longeroverall length than the primary lumen 252, so that the distal tip 308 ofstylet 306 not only abuts the distal closed end 262 of the primary lumen252, but the stylet hub 307 is exposed beyond the terminal hub 240 inthe fully assembled condition. When the stylet hub 307 is seated as aclosure in the terminal hub 240, a tension is created in the distal endportion 232 and the remainder of the catheter 230 by the forcedengagement of the distal tip 308 of the stylet 306 against the distalclosed end 262 of the primary lumen 252.

It will be recognized that a central feature of the invention is thatthe infusion and withdrawal thresholds of each three-position valve 234may be selected to meet the needs of any particular application. Inrespect to the embodiment of FIGS. 10-15 and 21, this may be donechemically, as previously described. In the case of the embodiment ofFIGS. 1-9, it is accomplished mechanically by providing a weakened hingeor fold line in the covering of the catheter tube. It is also to benoted that while the mechanically hinged valve is of particularimportance in multi-lumen catheters, the principles thereof, comprisingpart of the present invention, also apply to single-lumen catheters.

In FIG. 11, for example, the lumens 252, 253, 254 have a circular crosssection. Because of the convex curve of the valve wall 268, the valvelips 270 flex somewhat more easily outwardly than inwardly. As a result,the withdrawal threshold is typically somewhat higher than the infusionthreshold. Because the exterior surface 248 of the covering 233 is notconcentric with respect to the curvature of the lumens 252, 253, 254,the valve wall lips 270 increase in thickness with distance from eitherside of the slit 266. As a result, the valve 234 requires higherpressure differentials to open fully than it does to merely break theseal at the slit. By modifying the dimensional relationship between theinside walls 255 defining the interior lumens 252, 253, 254 and theoutside sheath surface 248 different valve threshold pressures andoperating characteristics may be obtained.

FIGS. 16-19 illustrate another presently preferred embodiment of thepresent invention, namely a two-lumen catheter generally designated 350in FIG. 16, constructed in accordance with the present invention forlong term indwelling use with a patient. A trocar (not shown), forexample may be used to position most of the proximal end of the catheter350 subcutaneously as hereinafter explained in greater detail. Theconstruction of the catheter 350 is essentially the same in manyrespects to the catheter 230. Therefore, only the differences will bedescribed.

The catheter 350 at the proximal end portion 352 thereof comprises twolumen-defining tubes 238. However the tubes 238 do not each terminate inhubs 240 as with catheter 230 of FIG. 1. Rather, the two tubes 238 arecollectively joined to a common hub structure 354.

FIG. 11 shows the presently preferred construction of the proximalcommon hub 354. The tubes 238 are brought together into side-by-sidecontiguous relation with their blunt trailing ends 356 aligned. Theleading blunt end 358 of a single short cannula 360 of hub structure 354is placed in close proximity to and generally in alignment with theblunt ends 356 of tubes 238. See FIG. 16. A suitable silicone rubberadhesive is extruded over the ends 356 and 358. A cylindrical sleeve 362is diametrically expanded by soaking it in freon, as previouslydescribed, and positioned over the joint so as to shrink into firmcontact with the adhesive and thus tightly seal the joint at either end.

The common cannula 360 is fitted at its proximal end with a stylet hub364 to which a stylet of the type previously disclosed is attached. Theuse of the stylet hub 364 connected to the common cannula 360 offers theadvantage of being able to simultaneously flush all of the lumenscomprised in the interior of the tubes 238 of the catheter 350 from asingle syringe (not shown) or the like.

Once the distal tip 242 of the catheter 350 is properly placed in adesired indwelling position by surgery or other methods known in theart, the stylet hub 364 and the attached stylet are removed from theproximal end. A trocar (not shown) is conventionally releasably attachedto the cannula 360. The trocar and the attached cannula 360 are thenpassed subcutaneously through the body to a convenient exit site.

Once the catheter 350 is properly placed, typically at a site readilyaccessible to the patient, the tubes 238 are transversely severed alongcut line 370 (FIG. 17) adjacent the coupling sleeve 362. Each severedend 372 of each tube 238 is thereafter fitted with a permanent terminalhub 374 by any suitable method. One such method is essentially disclosedin existing U.S. Pat. No. 4,547,194. The method illustrated in FIGS. 18and 19 comprises provision of the terminal hubs 374 which respectivelycomprise a short hollow shaft 376. The outside diameter of the shortshaft 376 is illustrated as being substantially the same as the outsidediameter of the tube 238. Accordingly, when the short shaft 376 isadvanced into the smaller diameter lumen-defining hollow interior of theassociated tube 238, as illustrated by lines 370 in FIG. 18, thetrailing end of tube 238 is stretched radially causing the insidediameter of the tube 238 to become the same as the outside diameter ofthe short shaft 376, as illustrated in FIG. 19. The memory of thesynthetic resinous material from which each tube 238 is made applies acompressive radial force against the short shaft 376 thereby retainingagainst inadvertent separation the described union created between eachhub 374 and the trailing end of the associated tube 238.

By placing the two trailing ends of the tubes 238 (with hubs 274 in theposition of FIG. 19) at a convenient body site accessible to thepatient, the patient himself may comfortably utilize the catheter 350.While during periods of non-use, the hubs 374 can be plugged withconventional plugs (not shown), the hubs during use, can be connected,for example, to an artificial kidney machine whereby blood from thesubclavian vein, for example, can be removed through one tube 238 forprocessing through the artificial kidney machine and the effluent fromthe machine can be returned to the bloodstream through the other tube238.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is, therefore, considered in all respects as illustrative andnot restrictive, the scope of the invention being indicated by the scopeof the appended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:
 1. An indwelling catheter tube comprising:(a) an elongatedbody of elastomeric material having an outside surface; (b) a lumenlongitudinally formed through said body of elastomeric material andcomprising a plurality of longitudinally extending inner wall surfaces,one of said inner wall surfaces in a cross section of said body ofelastomeric material taken normal to the longitudinal axis thereofcomprising a straight segment, the end points of said straight segmentbeing disposed closer to said outside surface of said body ofelastomeric material than the portions of said straight segmenttherebetween, thereby to define, between said straight segment and saidoutside surface of said body of elastomeric material radially outwardlyfrom said straight segment, a solid outer wall portion of said cathetertube integrally formed of said elastomeric material.
 2. A catheter tubeas recited in claim 1, further comprising a longitudinally extendingjuncture between said straight segment and the one of said inner wallsurfaces adjacent thereto, said juncture in a cross section of said bodyof elastomeric material taken normal to the longitudinal axis thereofbeing disposed closer to said outside surface of said body ofelastomeric material than portions of said straight segment and said oneof said inner wall surfaces proximate to said juncture.
 3. A cathetertube as recited in claim 2, wherein in said cross section of said bodyof elastomeric material said juncture comprises an arcuate fillettangentially connecting said adjacent pair of said inner wall surfaces.4. A catheter tube as recited in claim 2, wherein in said cross sectionof said body of elastomeric material said juncture comprises an arcuatefillet nontangentially interconnecting an end point of each of saidadjacent pair of said inner wall surfaces.
 5. A catheter tube as recitedin claim 2, wherein in said lateral cross section of said body ofelastomeric material said juncture comprises a linear inner wall segmentdisposed at an oblique angle to each of said adjacent pair of said innerwall surfaces.
 6. A catheter tube as recited in claim 2, wherein in saidcross section of said body of elastomeric material the portions of eachof said adjacent pair of said inner wall surfaces proximate to saidjuncture are substantially linear.
 7. A catheter tube as recited inclaim 1, wherein in a cross section of said body of elastomeric materialtaken normal to the longitudinal axis thereof one of said inner wallsurfaces of said adjacent pair of said inner wall surfaces comprises anarc, the end points of said arc being disposed closer to said outsidesurface of said body of elastomeric material than the portions of saidarc therebetween, thereby to define between said arc and said outsidesurface of said body of elastomeric material a solid outer wall portionof said catheter tube.
 8. A catheter tube as recited in claim 7, whereinthe radius of curvature of said arc is greater than the radius ofcurvature of the portion of said outside surface of said body ofelastomeric material opposite thereto.
 9. An indwelling catheter tubecomprising:(a) an elongated body of elastomeric material having anoutside surface; (b) a lumen longitudinally formed through said body ofelastomeric material and comprising a plurality of longitudinallyextending inner wall surfaces; and (c) prevention means associated witha first of said inner wall surfaces and said outside surface of saidelongated body of elastomeric material for preventing occlusion of saidlumen and for accommodating fluid flow in said lumen when negativepressure is applied to said lumen relative to said outside surface ofsaid body of elastomeric material, said prevention means comprising asolid outer wall portion of said catheter tube integrally formed of saidelastomeric material between said first of said inner wall surfaces andsaid outside surface of said elongated body of elastomeric materialradially outwardly from said first inner wall surface, the distance in across section of said body of elastomeric material taken normal thelongitudinal axis thereof measured normal to said outside surfacebetween said first of said inner wall surfaces and said outside surfaceradially outwardly from said first inner wall surface defining thethickness of said solid outer wall portion, said thickness thereofvarying from a maximum at the center thereof to a minimum at the endsthereof.
 10. An indwelling catheter tube as recited in claim 9, whereinin said cross section of said body of elastomeric material said first ofsaid inner wall surfaces comprises an arc.
 11. An indwelling cathetertube as recited in claim 9, wherein in said cross-section of said bodyof elastomeric material said first of said inner wall surfaces comprisesan straight segment.
 12. An indwelling catheter tube, comprising:(a) anelongated body of elastomeric material having an outside surface; and(b) a lumen longitudinally formed through said body of elastomericmaterial said lumen assuming a D-shape in a cross section of said bodyof elastomeric material taken normal to the longitudinal axis thereof,said D-shape assumed by said lumen in said cross section of said body ofelastomeric material comprising:(i) an arcuate inner wall surface; and(ii) a generally linear inner wall surface opposite said arcuate innerwall surface, the ends of said linear inner wall surface in said crosssection of said body of elastomeric material being disposed closer tosaid outside surface of said body of elastomeric material than any otherportions of said generally linear inner wall surface, thereby to define,between said linear inner wall surface of said lumen and said outsidesurface of said body of elastomeric material radially outwardly fromsaid first inner wall surface, a solid outer wall portion of saidcatheter tube integrally formed of said elastomeric material.
 13. Acatheter tube as recited in claim 12, wherein in said cross section ofsaid body of elastomeric material said juncture comprises an arcuatefillet tangentially connected to said adjacent pair of said inner wallsurfaces.
 14. A catheter tube as recited in claim 12, wherein in saidcross section of said body of elastomeric material said juncturecomprises an arcuate fillet nontangentially interconnecting an end pointof each of said adjacent pair of said inner wall surfaces.
 15. Acatheter tube as recited in claim 12, wherein in said cross section ofsaid body of elastomeric material said juncture comprises a linear innerwall surface disposed at an oblique angle to each of said adjacent pairof said inner wall surfaces.
 16. A catheter tube as recited in claim 12,wherein in a cross section of said body of elastomeric material takennormal to the longitudinal axis thereof said lumen generally assumes aquadrilateral shape.
 17. A catheter tube as recited in claim 12, whereinin a cross section of said body of elastomeric material taken normal tothe longitudinal axis thereof one of said inner wall surfaces of saidlumen is disposed opposite the outside surface of said body ofelastomeric material, thereby to define between said one of said innerwall surface of said lumen and said outside surface of said body ofelastomeric material a solid outer wall portion of said catheter tube,the distance in said cross section of said body of elastomeric materialbetween said one of said inner wall surfaces and said outside surfacemeasured normal to said outside surface defining the thickness of saidsolid outer wall portion, said thickness thereof varying from a maximumat the center thereof to a minimum at the ends thereof.
 18. A cathetertube as recited in claim 12, wherein in a lateral cross section of saidbody of elastomeric material taken normal to the longitudinal axisthereof said lumen generally assumes a polygonal shape.
 19. A cathetertube as recited in claim 18, wherein in said cross section of said bodyof elastomeric material two adjacent sides of said polygonal shape aretangentially joined by an arcuate corner segment.
 20. A catheter tube asrecited in claim 12, wherein in said cross section of body ofelastomeric material said lumen comprises a longitudinally extendingjuncture between said adjacent pair of said inner wall surfaces, saidjuncture in said lateral cross section of said body of elastomericmaterial taken normal to the longitudinal axis thereof being disposedcloser to said outside surface of said body of elastomeric material thanportions of said pair of said adjacent pair of said inner wall surfacesproximate to said juncture.
 21. An indwelling catheter tube,comprising:(a) an elongated body of elastomeric material having acylindrical outside surface; and (b) a lumen longitudinally formedthrough said body of elastomeric material, said lumen assuming aradially asymmetric shape in a cross section of said body of elastomericmaterial taken normal to the longitudinal axis thereof, said lumencomprising:(i) a plurality of longitudinally extending inner wallsurfaces; and (ii) a longitudinally extending juncture between each endof a first of said inner wall surfaces and the one of said inner wallsurfaces adjacent thereto, each of said junctures in said cross sectionof said body of elastomeric material being disposed closer to saidoutside surface of said body of elastomeric material than portions ofsaid first inner wall surface between said junctures, thereby to define,between said first inner wall surface of said lumen and said outsidesurface of said body of elastomeric material radially outwardly fromsaid first inner wall surface, a solid outer wall portion of saidcatheter tube integrally formed of said elastomeric material, thedistance in said cross section of said body of elastomeric materialmeasured normal to said outside surface between said first inner wallsurface and said outside surface radially outwardly from said firstinner wall surface defining the thickness of said solid outer wallportion, said thickness thereof varying from a maximum at the centerthereof to a minimum at the ends thereof.
 22. A catheter tube as recitedin claim 21, wherein in said cross section of said body of elastomericmaterial each of said junctures comprises an arcuate fillet tangentiallyconnected between said first of said inner wall surfaces and said one ofsaid inner wall surfaces adjacent thereto.
 23. A catheter tube asrecited in claim 21, wherein in said cross section of said body ofelastomeric material each of said junctures comprises an arcuate filletnontangentially interconnecting an end point of said first of said innerwall surfaces and an end point of said one of said inner wall surfacesadjacent thereto.
 24. A catheter tube as recited in claim 21, wherein insaid lateral cross section of said body of elastomeric material each ofsaid junctures comprises a linear inner wall segment disposed at anoblique angle to said first of said inner wall surfaces and said one ofsaid inner wall surfaces adjacent thereto.
 25. An indwelling cathetertube, comprising:(a) an elongated body of elastomeric material having anoutside surface; and (b) a plurality of lumens longitudinally formedthrough said body of elastomeric material, first and second lumens ofsaid plurality of lumens assuming a radially asymmetric shape in a crosssection of said body of elastomeric material taken normal thelongitudinal axis thereof, said first and second lumens eachcomprising:(i) a plurality of longitudinally extending inner wallsurfaces; and (ii) a longitudinally extending juncture between anadjacent pair of said inner wall surfaces, said juncture in said crosssection of said body of elastomeric material being disposed closer tosaid outside surface of said body of elastomeric material than portionsof said adjacent pair of said inner wall surfaces proximate to saidjuncture.
 26. A catheter tube as recited in claim 25, wherein in saidcross section of said body of elastomeric material each of said firstand second lumens assumes a D-shape, and wherein said first and secondlumens are so disposed within said body of elastomeric material that insaid cross section of said body of elastomeric material the curvedportions of said D-shapes are oriented toward the center of said crosssection.
 27. A catheter tube as recited in claim 25, wherein in saidcross section of said body of elastomeric material, one of said lumensassumes a polygonal shape and a vertex of said polygonal shape isdisposed closer to the other of said lumens than any other portions ofsaid polygonal shape.
 28. An indwelling catheter tube, comprising:(a) anelongated body of elastomeric material having an outside surface; and(b) a lumen longitudinally formed through said body of elastomericmaterial said lumen assuming a D-shape in a cross section of said bodyof elastomeric material taken normal to the longitudinal axis thereof,said D-shape comprising:(i) an arcuate inner wall surface; (ii) astraight inner wall surface opposite said accurate inner wall surface;and (iii) a longitudinally extending juncture between one end of saidstraight inner wall surface and an adjacent inner wall surface, saidjuncture in said cross section of said body of elastomeric materialbeing disposed closer to said outside surface of said body ofelastomeric material than portions of said straight inner wall surfaceand said adjacent inner wall surface proximate to said juncture.
 29. Anindwelling catheter tube as recited in claim 28, wherein said adjacentinner wall surface comprises one end of said arcuate inner wall surface.30. An indwelling catheter tube as recited in claim 28, wherein saidadjacent inner wall surface comprises a linear inner wall surfacetangentially connected to one end of said arcuate inner wall surface.31. An indwelling catheter tube, comprising:(a) an elongated body ofelastomeric material having an outside surface; and (b) first and secondlumens longitudinally formed through said body of elastomeric material,each of said first and second lumens in a cross section of said body ofelastomeric material taken normal the longitudinal axis thereof assuminga D-shape, said first and second lumens being so disposed within saidbody of elastomeric material that in said cross section of said body ofelastomeric material the curved portions of said D-shapes are orientedtoward the center of said cross section, thereby to strengthen thestructure of said body of elastomeric material to prevent occlusion ofsaid first and second lumens due to negative pressure applied thereto.32. An indwelling catheter tube, comprising:(a) an elongated body ofelastomeric material having a cylindrical outside surface; (b) first andsecond lumens longitudinally formed through said body of elastomericmaterial, each of said first and second lumens assuming a noncircularshape in a cross section of said body of elastomeric material takennormal to the longitudinal axis thereof, and each of said first andsecond lumens comprising:(i) first and second adjacent longitudinallyextending inner wall surfaces; and (ii) a longitudinally extendingjuncture between said first and second inner wall surfaces, saidjuncture in said cross section of said body of elastomeric materialbeing disposed closer to said outside surface thereof than portions ofsaid first and second inner wall surfaces proximate to said juncture insaid cross-section of said elastomeric body, said first inner wallsurfaces of said first and second lumens being disposed adjacent to eachother between said second inner wall surfaces; and (c) safety meansassociated with said first inner wall surfaces of said first and secondlumens for preventing occlusion of said first and second lumens toaccommodate fluid flow therein when said body of elastomeric materialtends to be kinked or laterally compressed by externally imposedstresses.
 33. A catheter tube as recited in claim 32, wherein saidsafety means comprises a solid internal portion of said body ofelastomeric material bounded in said cross section thereof by saidcylindrical outside surface and said first inner wall surfaces of saidfirst and second lumens, the distance in said cross section of said bodyof elastomeric material measured concentric with said cylindrical outersurface between said first inner wall surfaces of said first and secondlumens defining the thickness of said solid internal portion of saidbody of elastomeric material, said thickness thereof varying from amaximum at said junctures to a minimum radially centrally thereof insaid cross section of said body of elastomeric material.